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Astrophysics - Coggle Diagram

- - - - A large collection of billion of galaxies
    - - A large collection of billions of stars
    - - Sun in the centre of the solar system
      - Planets orbiting the sun
    - - A body that has a sufficiently large mass and that orbits a star. EXP: earth orbiting star(sun)
  - - - wheight is
        
        The force acting on an object due to gravitational attraction
      - The greater the mass of an object the greater the gravitational field strength
      - The further away from the planet the lower the gravitational strength
      - The mass of an object is always the same, but its weight changes depending on the gravitational field
    - - objects allways falling on the ground
      - objects staying on the ground
      - satellites being kept in orbit
    - - Gravity in earth is of 10N/Kg
      - Gravity on the moon is of 1.7N/Kg, this means it is less than in earth
      - https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/09/3.1.1.6-gravitational-field-strength-diagram.png
  - - - for example
        
        moon orbiting a planet
        
        asteroid orbiting the sun
        
        planets orbiting sun
    - - Always acts towards the centre of a larger body
      - Causes the orbiting object to move in a circular path
      - https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2020/05/gravity-orbits.png
    - - Orbital motion of planets
        
        They all orbit in the same plane
        
        They all travel in the same direction around the Sun
        
        Orbit is slightly eliptical and with the sun in the centre
        
        Differences between orbits in different planets
        
        Different planets take different time to loop the sun
        
        Different planets orbit at different speeds
        
        Different planets orbit at different distances from the sun
        
        The furthr away the slower the planet makes a full orbit
      - orbital motion of comets
        
        As the comet gets closer to sun the faster it travels
        
        As the comet gets further away from the sun, the slower the comet is
        
        Orbits are highly elliptical
      - Orbital motion of moons
        
        some planets have more than one moon
        
        the closer the moon is to the planet
        
        the shorter time to make a full orbit
        
        the greater the speed of the orbit
        
        orbit on a circular path
    - - The time taken for an object to complete one orbit
      - Orbital speed avarage equation
        
        V=2πr/t
        
        v=velocity
        
        r=avarage radius of orbit in m (the radius is taken from the centre of an object)
        
        t=orbital period in seconds
- - - - size
      - colour
        
        The star's colour determines its heat
        
        star's colour related to surface heat
        
        red which is colest (3000K)
        
        blue star is hottest (30000K)
        
        https://cdn.savemyexams.com/cdn-cgi/image/w=1920,f=auto/uploads/2021/09/8.2.1-Colour-of-Stars.png
        
        Colour changes in a star's life cycle
        
        When the star becomes a white dwarf the star heats up and contracts
        
        Star becomes a red giant when it becomes redder so it expands and cools down
  - - - Nebula. Stars form from a giant interstellar cloud of gas and dust called a nebula
        
        2.Protostar. The force of gravity within a nebula pulls the particles closer together until a hot ball of gas forms, known as a protostar
        
        3.Main sequence star. Once the protostar becomes hot enough, nuclear fusion reactions occur within its core
        
        The star runs out of hydrogen, running out of nuclear fusion. Then the star contracts, when the star is small enough nuclear fusion happens again and expands again. This process is repeated several times
        
        The star can now evolve into 2 different type of stars
        
        Red supergiant( stars a lot biger than the sun :
        
        1 more item...
        
        Solar mass star/red giant(star similar to the sun)
        
        2 more items...
        
        https://theplanets.org/123/2021/05/Life-Cycle-of-a-Red-Giant.png
        
        When fussion starts there is only gravity making the star contract
        
        When the star expands again, every element up to iron is formed
        
        Nuclear fusion starts to happen
        
        The star is in equilibrium (outward pressure of nuclear fusion and inward pressure of gravity are balanced out
        
        As particles get closer together the density of the protostar increases
        
        This results in more frequent collisions between the particles which causes the temperature to increase